Paymentwall widget version 2

$widget = new Paymentwall_Widget(
    $buyer_id,
    $widget_id,
    array(),
    array(
        'email'        => $buyer->user_email,
        'ref'          => $type,
        'customer'     => array( 'username' => $buyer->user_login, 'firstname' => $buyer->first_name, 'lastname' => $buyer->last_name ),
        'history'      => array( 'registration_date' => strtotime( $buyer->user_registered ) ),
        'sign_version' => 3,
        'test_mode'    => $this->prefs['sandbox'], // 1 = yes 0 = no
        'pingback_url' => $this->callback_url(), // www.mywebsite.com/?mycred_call=paymentwall
        'success_url'  => $this->get_thankyou() // thank you url
    )
);